Inorganic chemistry

• 1. block elements

  Elements of group 3-12 in the periodic table
• General electronic configuration of d-block elements

  (n-1)d" ns but this has several exceptions due to very little energy difference between (n - 1)d and ns orbitals
• Series of transition metals

  • 3d series (Sc to Zn)
  • 4d series (Y to Cd)
  • 5d series (La and Hf to Hg)
  • 6d series (Ac and Rf to Cn)
• Zn, Cd and Hg are not regarded as transition metals
• Transition metals

  • With the exceptions of Zn, Cd, Hg and Mn, these have one or more typical metallic structures at normal temperatures
• Tungsten (W) has highest melting point among d-block elements
• Lanthanoid contraction

  The filling of 4f before 5d orbitals results in a regular decrease in atomic radii, the net result of which is that the 2 and 3 d-series exhibits similar radii (e.g. Zr and Hf)
• Mn exhibits all the oxidation states from +2 to +7
• Sc(II) virtually unknown
• The only oxidation state of Zn is +2
• In group-6, Mo(VI) and W(VI) are found to be more stable than Cr(VI)
• Reactivity of 3d series elements

  • Among 3d series elements, E°(M²/M) is positive only for copper because high energy to transform Cu(s) to Cu (aq.) is not balanced by its hydration enthalpy. Only oxidising acids (nitric and hot concentrated sulphuric) reacts with Cu
  • Among 3d series, the value of E (M2+M) for Mn, Ni and Zn are more negative than excepted from the trend
• Disproportionation

  Many Cu(I) compounds are unstable in aqueous solution and undergo disproportionation
• Ferrates (FeO4)2- are formed in alkaline media but they readily decompose to Fe2O3 and O2
• The highest Mn fluoride is MnF4 whereas highest oxide is Mn₂O7
• Mn2

  A covalent oxide in which each Mn is tetrahedrally surrounded by O's including Mn-O-Mn bridge
• Order of oxidising power

  • VO2 < Cr₂O7 <MnO
• Ti & V, in practise, are passive to dilute non-oxidising acids at room temperature
• Oxidising and reducing power of 3d series ions

  • E (M³*/M²*) values shows that Mn3* and Co³* ions are strongest oxidising agents in aqueous solutions among 3d series
  • The ions TI²* , V²* and Cu²* are strong reducing agents among 3d series and will liberate H2, from dilute acids
• Magnetic moment

  Each unpaired electron has a magnetic moment associated with its spin angular momentum and orbita angular momentum
• Spin only formula

  For the compounds of first transition series metals magnetic moment is determined by 'spin only' [ μ = √n(n+2) BM ]
• 1. block elements

  Elements in which 4f and 5f orbitals are progressively filled, also known as inner-transition elements
• Series of inner transition elements

  • 4f (Ce to Lu) - Lanthanoids
  • 5f (Th to Lr) - Actinoids
• Lanthanoids

  Series of inner transition elements where 4f orbitals are progressively filled
• Outer electronic configuration of lanthanoids

  4f^1-14 5d^0-1 6s^2
• Lanthanoids


  • Overall decrease in atomic and ionic radii from La to Lu due to poor shielding to 4f - Lanthanoid contraction
  • Most common oxidation state is +3
  • Pr, Nd, Tb and Dy also exhibit +4 oxidation state but only in oxides, MO2
  • Eu and Yb also exhibit +2 oxidation states
  • Melting point range between 1000 to 1200 K but Sm melts at 1623 K
  • Ln^3+ ions may be coloured due to presence of f-electrons
  • Form Ln(OH)3, which are basic like alkaline earth metal hydroxides
  • Mischmetal is an alloy which consists lanthanoids (~95%) and Iron (~5%)
• Actinoids

  Series of inner transition elements where 5f orbitals are progressively filled
• Actinoids

  • Outer electronic configuration: 5f^0-14 6d^1 7s^2
  • All actinoids are radioactive elements
  • Gradual decrease in the size of atoms or M^3+ ions across the series known as actinoid contraction, which is greater than lanthanoid contraction
  • Their general oxidation state is +3 but these elements can show variety of oxidation states
• application of d and f :

  1. TiO is used in pigment industry
  2. MnO2 is used in dry battery cell
  3. TiCl2 and Al(CH3)3 , ziegler catalyst is used to manufacture polyethene
  4. PdCl2 is used as catalysts in walkers process
  5. AgBr is used in photographic industry
• These metals

  • Form a large number of complex compounds due to comparatively smaller sizes of the metal ions, their high ionic charges and the availability of d-orbitals for the bond formation
• These metals and their compounds

  Used as a catalyst due to their ability to adopt multiple oxidation states and to form complexes
• Interstitial compounds

  When small atoms like H, C or N are trapped inside the crystal lattice of these metals, the combination are called interstitial compounds which are usually non-stoichiometric
• Due to similar radii, transition metals form alloy
• Alloys

  • Brass (Cu-Zn)
  • Bronze (Cu-Sn)
• Manganese (VI) becomes unstable relative to manganese (VII) and manganese (IV) in acidic solution


  3MnO²4+4H→2MnO4 + MnO2 + 2H₂O
• 3d metals forms MO oxides

  • Except scandium
• KMnO4 oxidises I- into I and IO3- respectively


  In acidic and faintly alkaline medium
• Permangnate titrations in presence of HCI are unsatisfactory since HCI is oxidised to Cl₂
• Oxide nature :

  • 
Mn2O7 is acidic
  • Cr₂O3 is amphoteric
  • CrO is basic
• With the exception of Zn, Cd, and Hg, these metals are very hard and have low volatility